This invention relates to a method of attracting the Mediterranean fruit fly by subjecting the Mediterranean fruit fly to an attractant, wherein the attractant is ethyl (1R,2R,5R)-5-iodo-2-methylcyclohexane-1-carboxylate in an enantomeric excess of at least 70% and a regio and diastereo chemical purity of  greater than 5:1. The compound ethyl (1R,2R,5R)-5-iodo-2-methyl cyclohexane-1-carboxylate, in an enantomeric excess of at least 70% and a regio and diastereochemical purity of  greater than 5:1, may be prepared by reacting ethyl (1R,2R,5S)-5-hydroxy-2-methyl-1-carboxylate with Ph3P-imidazole-I2 (or Ph3P-2,6-lutidine-I2) in a carbon tetrachloride/methlylene chloride mixture.
The Mediterranean fruit fly, Ceratitas capitata (Wiedemann) commonly known as the medfly, is a worldwide pest that feeds on 253 fruits and vegetables (Liquido, N. J., et al., Misc. Publ. Entomol. Soc. Am., 77:1 (1991)). The establishment of this exotic pest into the continental United States would significantly increase pesticide use and curtail fruit and vegetable exports, a multi-billion dollar industry (Jackson, D. S., et al., Entomol. Soc. Am., 31:2937 (1985)). For more than 30 years trimedlure (TML), a mixture of sixteen regio- and stereoisomers of tert-butyl esters of 4 (and 5)-chloro-2-methylcyclohexane-1-carboxylate (1), has been widely used as an attractant in traps used to monitor and detect male medfly (Beroza, M., et al., J. Agric. Food Chem., 9: 361-365 (1961)). The commercial trimedlure is formulated in a polymeric plug-type dispenser containing 2 g of trimedlure which acts as a controlled release dispenser for up to 8 weeks in Jackson traps (Leonhardt, B. A., et al., J. Econ. Entomol., 82: 860-867 (1989); Leonhardt, B. A., et al., Entomol. Exp. Appl., 44: 45-51 (1987)). HPLC separation of these sixteen regio- and stereoisomers of tert-butyl esters of 4 (and 5)-chloro-2-methylcyclohexane-1-carboxylate (1) made possible a field study of the relative attractiveness of these racemates toward the Mediterranean fruit fly (McGovern, T. P., et al., J. Econ. Entomol., 83:1350-1354 (1990)). Of these stereoisomers, TML-C (2) was shown to be most active. Particularly noteworthy is the ability of the medfly to discriminate among the two enantiomers of TML-C, with the (1S, 2S, 4R) configuration being most attractive (Sonnet, P. E., et al., J. Org. Chem., 49: 4639-4643 (1984); Doolittle, R. E., et al., J. Chem. Ecol., 17: 475-484 (1991)). 
Recently, an iodo analog of trimedlure, ceralure (CER) (3), a mixture of 16 regio- and stereoisomers of ethyl 4 (and 5)-iodo-2-methylcyclohexane-1-carboxylate, has been found to be a more persistent and potent attractant than TML (U.S. Pat. No. 4,764,366). A field study designed to measure the relative attractiveness of these racemates, which were tediously separated by HPLC, demonstrated that ethyl cis-5-iodo-trans-2-methylcyclohexane-1-carboxylate (CER B1) (4) is most active (Warthen, J. D., J. Chem. Ecol, 20: 569-578 (1994)). 
We have discovered that ethyl (1R,2R,5R)-5-iodo-2-methylcyclohexane-1-carboxylate, in an enantomeric excess of at least 70% and a regio- and diastereochemical purity of  greater than 5:1, may be prepared by reacting ethyl (1R,2R,5S)-5-hydroxy-2-methyl-1-carboxylate with Ph3P-imidazole-I2 (or Ph3P-2,6-lutidine-I2) in a carbon tetrachloride/methlylene chloride mixture.
In accordance with this discovery, it is an object of the invention to provide ethyl (1R,2R,5R)-5-iodo-2-methylcyclohexane-1-carboxylate in an enantomeric excess of at least 70% and a regio- and diastereochemical purity of  greater than 5:1.
It is another object of the invention to provide a composition for attracting the Mediterranean fruit fly wherein the composition contains ethyl (1R,2R,5R)-5-iodo-2-methylcyclohexane-1-carboxylate in an enantomeric excess of at least 70% and a regio- and diastereochemical purity of  greater than 5:1.
It is also another object of the invention to provide a method of attracting the Mediterranean fruit fly by subjecting the Mediterranean fruit fly to an attractant, wherein the attractant is ethyl (1R,2R,5R)-5-iodo-2-methylcyclohexane-1-carboxylate in an enantomeric excess of at least 70% and a regio- and diastereochemical purity of  greater than 5:1.